1. Field of the Invention
The present invention relates to a packet relay method and device, and in particular to a packet relay method and device which divide a packet into segment data of a predetermined length to be relayed.
2. Description of the Related Art
A prior art example of a packet relay method and device as mentioned above will now be described referring to FIG. 25.
Prior Art Example: FIG. 25
In input side interface cards 10_1-10—n (hereinafter, occasionally represented by a reference numeral 10) composing a packet relay device 1 shown in FIG. 25, receivers 11_1-11—n respectively receive packets PD from the preceding stage, and segment data dividers 12_1-12—n (hereinafter, occasionally represented by a reference numeral 12) divide the received packets PD into segment data SD of a predetermined length to be sequentially provided to a switch card 20.
The segment data SD includes a destination address of the packet PD in its header. The switch card 20 having received the data performs sorting (hereinafter, referred to as switching) the segment data SD to any of output side interface cards 30_1-30—n (hereinafter, occasionally represented by a reference numeral 30) according to the destination address.
In the output side interface cards 30_1-30—n having received the segment data SD to which the switching is performed, packet assembling portions 31_1-31—n (hereinafter, occasionally represented by a reference numeral 31) respectively assemble the packets PD from the segment data SD, and transmitters 32_1-32—n transmit the packets PD assembled to the subsequent stage.
Thus, by switching the packets per segment data, a priority control of packets (for example, when a packet whose priority is higher than that of the packet antecedently inputted is received, the switching is performed to the segment data of the packet with higher priority before the segment data of the packet with lower priority antecedently inputted) or the like can be performed, thereby guaranteeing a communication quality of the packet.
It is to be noted that as reference examples, the following (1) and (2) can be mentioned:
Reference Example (1)
A packet processing device which enqueues an inputted packet to any of a plurality of queues according to its class (priority), and dequeues the packet from the queue selected by performing scheduling and a bandwidth calculation based on the class, the number of segment data upon dividing the inputted packet per a predetermined length, and the total number of segment data within the queues (see e.g. patent document 1).
Reference Example (2)
A packet relay device which refers a multipath routing table in which a plurality of different path information are set per destination address when a plurality of packets with the same destination address are provided to input side interface cards, thereby selectively sorting the packets to at least two output side interface cards according to the path information (see e.g. patent document 2).    [Patent document 1] Japanese patent application laid-open No. 2005-286383    [Patent document 2] Japanese patent application laid-open No. 2006-165952
With a recent increase of packet communication traffic, the number of segment data transferred within the packet relay device tends to increase.
In this case, the segment data transmitted from the input side interface cards may concentrate in the switch card in the prior art example shown in FIG. 25. Accordingly, there has been a problem that the switching process is congested, which leads to a transmission delay, missing, etc. of the packet.